Medico-surgical tubes, such as tracheostomy tubes, are commonly provided with a flange to secure the tube to the patient's body. In the case of a tracheostomy tube, the flange is positioned close to the surface of the neck where the tube enters the tracheostomy, a tape being threaded through openings in the flange and fastened around the neck. For most patients, a comfortable fit can be achieved using one of a range of several different size tubes, each having a flange mounted at a fixed location along the tube suitable for patients having an average anatomy. There are, however, some situations where a fixed flange is not suitable, such as, for example, in obese patients where tissue between the neck surface and the trachea is very thick. In these situations, it is preferable for the flange to be movable along the tube to the ideal position and to be lockable in that position. Tubes with adjustable flanges are described in, for example, U.S. Pat. Nos. 5,026,352, 4,249,529, 4,449,527, 4,498,903, 4,530,354, 4,530,354, 4,649,913, 4,683,882, 4,774,944, WO80/02645, WO84/03217, U.S. Pat. No. 4,278,081 and WO06/087513. U.S. Pat. No. 8,104,476 describes a tube with an adjustable flange having two halves that clamped about the outside of a tube when a lever is folded flat. It is important to achieve a secure fastening of the flange to the tube even when this is wet and slippery. Because of this the flange must exert a relatively high frictional force on the outside of the tube. This can cause a problem in that the outside of the tube may be compressed by the flange, leading to a permanent or semi-permanent indentation in the outside of the tube, which may also cause a localised reduction in the diameter and cross-sectional area of the bore through the tube.
It is an object of the present invention to provide an alternative medico-surgical tube assembly and flange assembly for a medico-surgical tube assembly.